Hamilton appeared to be struggling with his car throughout the day - he aborted his first two attempts at a fast lap, made a series of mistakes and was slower than Bottas in both sessions.

"It has generally been a tricky day," said Hamilton. "The Ferrari is definitely quickest as they have been all year so far and we will work to try to pick up some pace tomorrow."

"If we can get out tyres working properly I think we can be closer and similar. There is no difference to our car compared to the previous races so the gap is still very close between us as it has been in the past."

The Red Bulls of Max Verstappen and Daniel Ricciardo were fifth and sixth but 1.4 seconds off Vettel's pace, and the Dutchman ground to a halt with an engine problem midway through the session.

It was another difficult day for McLaren-Honda. Stoffel Vandoorne suffered an engine problem at the end of the first session which required a change of power-unit.

That has resulted in the Belgian receiving a 15-place grid penalty because he has already used too many of the six constituent parts of the engine. Vandoorne is now on his fifth turbocharger and fifth MGU-H, the part of the hybrid system that recovers energy from the turbo, when only four changes are permitted in the entire 20-round season.